So bad news for you. It seems you can't use Bluetooth (it only plays out the single device you are connected to, no stereo pairing, don't know if this will/can be fixed, I'm assuming no)

I have heard that the audio input jack, when configured as an input, does not support pairing either, again, only plays out of device it's plugged into (SUB has no input jack, so splitter wouldn't help for that. I wouldn't know, since there is a bug preventing the line-in jack from being configured at the moment. Another pre-mature device release from Amazon, evidently. I don't know if this will/can be fixed either. Hope so.

So it seems, stereo paired 2.1 output only works with streaming audio sources like Amazon Music and Spotify, no other source works with it, which will result in mine getting returned if no fix by end of Jan.